VC-SELs are known. See, for instance, G. Hasnain et al., IEEE Journal of Quantum Electronics, Vol. 27, No. 6, pp. 1377-1385 (1993), and D. Vakhshoori et al., Applied Physics Letters, Vol. 62, pp. 1448-1450 (1993). Such devices are potentially attractive for, e.g., system applications requiring an array of lasers, e.g., for 2-dimensional optical processing. VC-SELs can have low power consumption, typically emit a beam of radiation having circular cross section, and can be produced with high yield. These are all desirable attributes. However, prior art VC-SELs typically also have an undesirable attribute, namely, lack of polarization stability. As those skilled in the art will realize, polarization instability results in polarization partition noise, and is inherently detrimental for systems requiring coherent and high speed laser operation. Furthermore, even if the polarization were fixed, as long as the polarization is randomly oriented the design of optical systems will be complicated by this randomness. Desirably, the polarization should be linearly fixed in a pre-determined direction.
Attempts have been made to produce a polarization-stable VC-SEL by applying biaxial stress, and by transverse mode engineering. See T. Mukaihara et al., IEEE Photonic Technology Letters, Vol. 5, pp. 133-135 (1993), and K. D. Choquette et al., "Conference on Lasers and Electro-Optics" (IEEE/OSA, Baltimore, Md. 1993), p. 148, CTuN1, respectively). However, these approaches are difficult to implement, and typically do not provide a satisfactory solution to the mode instability problem. In view of the potential advantages of a polarizations-table VC-SEL, it would be highly desirable to have available a relatively simple, readily manufacturable polarization-stable VC-SEL with a predetermined polarization direction. This application discloses such a device.